1. Field of the Invention
The present invention relates to a connection belt connecting rolling members for holding the rolling members, to be rotatably, rolling along a path defined by a track member and a movable member of, for example, a linear guide, ball spline and the like and also relates to a motion guide device provided with such rolling member connection belt.
2. Related Art
A linear guide is generally composed of a track rail, a movable block assembled to the track rail to be movable relative to the track rail and a number of balls as rolling members disposed between the track rail and the movable block.
FIG. 8 shows one example of such linear guide, in which balls 1 roll in a passage or path defined by the track rail 2 and the movable block 3 and are scooped up by an end cap 4 at each of the end portions of the movable block 3. The balls 1 then roll in a ball return passage 5 formed in the movable block 3 and return to the ball rolling passage formed between the track rail 2 and the movable block 3 through another end cap 4 formed at the other end portion of the movable block 3.
A rolling member retainer is a member for holding and retaining the balls 1 so that the balls 1 roll and move smoothly in the ball rolling passage without contacting to each other.
In a linear guide provided with a separate-type retainer, a plurality of retainers each disposed between the balls are arranged independently, i.e., separated from each other in arrangement.
On the other hand, in a linear guide provided with a connection-type retailer, as shown in FIG. 9, a plurality of retainers 6, 6, - - - disposed between the balls 1 are connected by a belt 7. Each of these retailers 6 is disposed between adjacent balls 1 to thereby prevent the balls 1 from contacting each other. In such connection-type retainer, the balls 1 can be guided in the ball advancing direction with a constant distance being maintained between the adjacent balls 1, thus the movable member being smoothly moved.
In general, such retainer for the rolling members (which may be called hereinlater merely “retainer”) is manufactured through an injection molding process using a resin material such as elastomer. In the connection-type retailer, it has been required to make compact the retainer according to recent requirement of compact-sized linear guide. However, in the structure made to satisfy such requirement for compactness, there may often causes short-circuited and, moreover, it becomes difficult to carry out the injection molding. In addition, it is also difficult to ensure high strength at the connection portion of the retainer and the belt therefor.
In order to solve the defects or inconvenience described above, the applicant of the subject application has provided a rolling member retainer manufactured through a pressing working of a metal plate member such as disclosed in Japanese Patent Laid-open (KOKAI) Publication No. 2000-65053, in which the rolling member retainer made from the metal material is formed with a number of ball retaining (holding) holes at a predetermined distance between the adjacent ones and the ball is retained in each of the ball retaining holes to be rotatable.
Generally, as shown in FIG. 8, a circulation passage of a linear guide through which the balls circulates has a circuit structure configured such that a loaded rolling passage and a non-loaded return passage, both extending linearly, are connected, at both end portions, by a pair of U-shaped rolling direction changing passages. Because of such structure, the rolling member retainer circulates in the circulation passage in the linearly extending fashion in the loaded rolling passage and non-loaded return passage and also in the bent fashion in U-shape in the direction changing passages. The rolling member retainer is moved and circulated while repeatedly taking the above fashions in the circulation passage.
In the above meaning, if the rolling member retainer is made of metal material, there may cause a case that the retainer are not sufficiently bent in the desired shape during the circulating motion in the direction changing passages, and hence, the smooth circulation of the rolling members therein may be obstructed.